A single-center, prospective, single-arm, phase II trial to evaluate the adjuvant efficacy of camrelizumab with docetaxel plus S-1 for stage III (PD-L1+/dMMR/EBV+) gastric cancer after D2 resection.

e16089 Background: Immunotherapy has demonstrated promising efficacy and favorable safety profile for unresectable or metastatic gastric cancer (GC) by several high-quality studies. However, few have examined the immunotherapy efficacy for locally advanced GC (LAGC) in the perioperative setting, especially as adjuvant therapy after D2 resection. Here, a phase II trial reports the adjuvant efficacy of camrelizumab with docetaxel plus S-1 in patients (pts) with PD-L1 positive, deficient mismatch repair (dMMR) or Epstein-Barr virus (EBV) positive LAGC (NCT04152889). Methods: This is a single-center, prospective, open-label and single-arm phase II study. Chemotherapy-naive adult pts receiving D2 resection and histologically confirmed as PD-L1 positive (CPS > 5), dMMR or EBV positive LAGC (stage III) were enrolled. Pts received camrelizumab (200mg, D1), docetaxel (40mg/m 2 , D1, free at first course) and S-1 (80-120mg, D1-14) every 3 weeks for seven courses, sequenced by camrelizumab (200mg, D1) and S-1 (80-120mg, D1-14) every 3 weeks for up to one year, until disease relapse or intolerable toxicity. Primary endpoint was 1-year relapse-free survival (RFS). Herein, the safety and efficacy data after 1-year postoperative therapy courses were reported. Results: From Jan. 2020 to Jan. 2022, 19 pts (median age 59 years, range 34-75, 13 men and 6 women) were enrolled, of whom 15 were CPS > 5, 3 were dMMR, and 1 was EBV positive. pTNM stage IIIA, B and C were 10 (52.6%), 3 (15.8%) and 6 (31.6%), respectively. The cut-off date for the final follow-up data was Feb. 1, 2023 with a median follow-up period for surviving patients of 25.1 months. All 19 pts had experienced treatment related adverse events (TRAEs), of whom, grade 3-4 TRAEs occurred in 9 (47.4%), 2 pts (10.5%) discontinued therapy, and 11 pts (57.9%) delayed the therapy. Furthermore, the OS rate of 19 pts at 1/2 years was 100% and 88.9%, while the RFS rate at 1/2 years was 100% and 92.3%, respectively. The dead and recurrent cases all belonged to PD-L1 positive subgroup. Conclusions: Adjuvant therapy of camrelizumab with docetaxel plus S-1 shows acceptable safety and promising efficacy for PD-L1 positive, dMMR, or EBV positive stage III GC pts after D2 resection. Clinical trial information: NCT04152889 .